Many UV light absorbers are known as ingredients for polymeric materials used to make ophthalmic lenses. UV absorbers are preferably covalently bound to the polymeric network of the lens material instead of simply physically entrapped in the material to prevent the absorber from migrating, phase separating or leaching out of the lens material. Such stability is particularly important for implantable ophthalmic lenses, especially intraocular lenses (IOLs), where the leaching of the UV absorber may present both toxicological issues and lead to the loss of UV blocking activity in the implant.
Numerous copolymerizable benzatriazole, benzophenone and triazine UV absorbers are known. Many of these UV absorbers contain conventional olefinic polymerizable groups, such as methacrylate, acrylate, methacrylamide, acrylamide or styrene groups. Copolymerization with other ingredients in the lens materials, typically with a radical initiator, incorporates the UV absorbers into the resulting polymer chain. Incorporation of additional functional groups, on a UV absorber may influence one or more of the UV absorber's UV absorbing properties, solubility or reactivity. If the UV absorber does not have sufficient solubility in the remainder of the ophthalmic lens material ingredients or polymeric lens material, the UV absorber may coalesce into domains that could interact with light and result in decreased optical clarity of the lens.
Examples of polymeric ophthalmic lens materials that incorporate UV absorbers can be found in U.S. Pat. Nos. 5,290,892; 5,331,073 and 5,693,095.
Likewise, copolymerizable short wavelength light absorbing chromophores are known as ingredients for polymeric materials used to make ophthalmic lenses. Blue-light absorbing chromophores include those disclosed in U.S. Pat. Nos. 5,470,932 and 5,543,504.
In order to obtain polymeric lens materials that absorb both UV and short wavelength visible light (e.g., 400-500 nm), it is common to add separate UV-absorbing and short wavelength light-absorbing chromophores to the polymeric materials. For example, the AcrySof® Natural IOL product, which is commercially available from Alcon Laboratories, Inc., contains a UV absorber and a blue-light absorber.
Having a single chromophore that absorbs both UV and short wavelength visible light would be advantageous. Such a single chromophore would reduce the number of components that are added to a lens material formulation and reduce disruption to the primary polymer chain structure produced by the lens formulation's primary monomer constituents.